a tubular trap housing;

a first cover having a first cover plate connected to and covering one end of the trap housing, and an inlet at a central portion of the cover plate, the inlet defining a passageway leading into the trap housing;

a heater disposed adjacent the inlet so as to heat gaseous byproducts entering the trap housing through the inlet;

a second cover having a second cover plate connected to and covering the other end of the trap housing, and an outlet at a central portion of the second cover plate, the outlet defining a passageway leading out of the trap housing;

a first cooling plate disposed within and extending across the trap housing, the first cooling plate having a plurality of exhaust holes extending therethrough at the outer peripheral portion thereof;

a second cooling plate disposed within and extending across the trap housing as spaced from the first cooling plate in the axial direction of the trap housing, the second cooling plate having a circular exhaust hole extending through a central portion thereof;

a single post disposed coaxially with the trap housing, the post comprising a pipe spaced radially inwardly of the trap housing such an annular space is delimited by and between the pipe and an inner surface of the housing, the pipe extending from a central portion of the first cooling plate to a central portion of the second cooling plate and connecting the central portions so as to space the first and second cooling plates in the axial direction of the trap housing, said post and the pipe having an inner diameter at least equal to the diameter of the exhaust hole of the second cooling plate, and a plurality of ventilation openings extending radially therethrough so as to open into the annular space delimited by and between the pipe and the inner surface of the housing; and

a cooling system defining a first cooling passageway in each of the cooling plates.